1.1 Overview of gemcitabine Gemcitabine (29,29-difluoro 29-deoxycytidine, dFdC) which developed from cytosine arabinoside (Ara-C) is an nucleoside analog used as chemotherapy. It was intended as an antiviral drug in initial, but preclinical testing showed that it killed leukemia cells and a spectrum of solid tumor in vitro. In cell, gemcitabine undergoes complex intracellular conversion to the active forms of nucleotides gemcitabine diphosphate (dFdCDP) and triphosphate (dFdCTP) that will influence DNA synthesis. dFdCTP competes with deoxycytidine triphosphate (dCTP) and dFdCDP is a potent inhibitor of ribonucleoside reductase (1). Gemcitabine is administered by the intravenous route with dose ranges from 0.6-1.2 g/m^2 of body surface area (2), and has been used in a broad spectrum cancer management including lung, breast, pancrease, and bladder (3).